1. Field of the Invention
The present invention relates to a method for checking and adjusting a speed governor of an elevator for carrying passengers or freight from one level to another.
2. Description of the Prior Art
FIG. 1 is a front view depicting a general construction of a conventional elevator governor (hereinafter referred to simply as a governor) checking and adjusting system disclosed, for instance, in Japanese Pat. Appln. No. 7-190922; FIGS. 2(a) and (b) are partly enlarged front and plan views of the governor checking and adjusting system shown in FIG. 1.
In FIG. 1, reference numeral 12 denotes an elevator car; 13 denotes a base of the governor mounted on the roof of the elevator car 12; 14 denotes arms rotatably attached to a rotary shaft 15 of the base 13; 16 denotes a magnet assembly connected to the arms 14 at one end thereof to detect overspeeding of the elevator car 12; 16a denotes a pair of opposed magnets bonded on a U-shaped back yoke 16b; 17 denotes a balance weight mounted on the arms 14 at the other end thereof such that it balances with the magnet assembly; and 18 denotes a pair of fixed conductive guide rails extending vertically along both sides of the elevator car 12.
The magnet assembly 16 comprises the pair of magnets 16a disposed opposite one of the fixed conductive guide rails 18 and the back yoke 16b providing a path for magnetic fluxes emanating from the two magnets 16a. The arms 14, the rotary shaft 15 of the base 13, the magnet assembly 16 and the balance weight 17 constitute a force detecting mechanism.
Reference numeral 19 denotes springs both support the arms 14 and convert force exerted on the balance weight 17, that is, a reaction force, to displacement of the balance weight 17; 20a denotes an elevator car stop switch which is actuated by the displacement of the balance weight 17; 31 denotes emergency brakes; and 32 denotes a cam for actuating a latch mechanism described below. The cam 32 is connected to one end of the rotary shaft 15, and consequently the cam 32 turns as the rotary shaft rotates.
Reference numeral 33 denotes a latch arm, 34 a latch shaft, 35 a coupling arm, and 36 a latch pin, which constitute the latch mechanism that operates in ganged relation to the cam 32. Reference numeral 21 denotes a pull-up rod, and 22 pull-up springs, which constitute a transmission for transmitting instructions for the actuation of the emergency brakes 31, the pull-up rod 21 being coupled by the latch pin 36 to the latch mechanism.
The elevator employing the present invention is of the type that the elevator car 12 for freight or passengers moves up and down in an elevator hoistway in a steel tower or high-rise building and that a speed governor is loaded on the elevator case 12 as a substitute for governor ropes used in the past. In a machine room at the top of the elevator hoistway there are provided a hoist, a switchboard (both not shown) and so on; the elevator car 12 and a balance weight (not shown) hang from the hoist such that the elevator car 12 is moved up and down just like a well bucket. In the elevator hoistway there are provided the fixed conductor guides 18 for the elevator car 12 and the balance weight, and in a pit at the bottom of the elevator hoistway there are placed buffers (not shown) for the elevator car 12 and the balance weight.
The above-described governor operates as follows.
As depicted in FIGS. 2(a) and (b), the magnet assembly 16 made up of the magnets 16a and the back yoke 16b produces a magnetic field in the flange or vane of the fixed conductive guide rail 18 positioned between the opposed magnets 16a. Upon the magnetic field traveling in the fixed conductive guide rail 18 as the elevator car 12 moves up or down, an eddy current is induced in the guide rail 18 which cancels intensity variations of the magnetic field, causing the magnet assembly 16 to produce an electromagnetic reaction force of a magnitude corresponding to the speed of the elevator car 12 in a direction opposite to the up or down run direction of the elevator car 12. The reaction force thus produced is converted by the arms 14 and the springs 19 to upward or downward displacement of the magnets 16a and the balance weight 17.
When the ascent/descent speed of the elevator car 12 has reached a first overspeed value (normally approximately 1.3 times higher than a rated speed, see FIG. 3) in excess of a predetermined value, a force corresponding to the increased speed of the elevator car 12 is exerted on the magnet assembly 16, causing the balance weight 17 to be displaced accordingly. And, when this displacement reaches a first operating point, the elevator car stop switch 20a equipped in a brake operates to tun off the power supply of the elevator drive system, bringing the elevator car 12 to a stop. Even in the case where the ascent or descent speed of the elevator car 12 reaches a second overspeed value (normally about 1.4 times higher than the rated speed, see. FIG. 3) for some reason and the displacement of the balance weight 17 goes up to a second operating point, the balance weight 17 is further displaced corresponding to the increased speed of the elevator car 12, and the cam 32 ganged with the balance weight 17 turns, causing the latch arm 33 to enter into a recess 30 of the cam 32. Then the pull-up rod 21 is pulled down by the pull-up springs 22 through the latch mechanism, and the emergency brakes 31 mounted on the elevator car 12 are actuated to drive wedges into the fixed guide rails 18, bringing the elevator car 12 to a quick stop by friction.
Such a speed governor must be checked for normal operation responsive to the overspeeding elevator car at the time of installation or maintenance, but no method therefor has been established so far. And the speed governor may sometimes need on-site adjustment, but no system or scheme therefor has been implemented, either.
Because of such a construction as described above, the conventional governor has a problem that no methods have been established for checking and adjusting its operation during on-site installation or maintenance.